Disintegrable sealing member



Oct. `12, 19754 R. A. WHITMORE 0m N wl. n. M W 0 e ings.

Patented Oct. 12, 1954 UN IT'E'D STATES I'P- if l,-oFf-ricapIsINTEcR-ABLE sEALING MEMBER Raymond A. Whitmore, Alhambra, Calif.,assigner toi LanelWells' Company, LosAngeles, Calif.,1 a

corporation of Delaware Application December 14, 1950,.Serial No;200,824

(CLZZIi-ZW 2 claims. 1

This inventionv relates to gun perforators and ymore specically to uidseals ofthe type .used

located either gun units including'suitable pro-fwk .pulsive chargechambers and barrels adapted t re' bullets through the openings, vorexplosive shaped charges which project jets of highkvelocity gases topierce the casing or formation. Inorder vtotadaptV such tools to beingloweredinto fluid filled Well boreholes and'casings, it `is of coursedesirable to seal the discharge openings in the gun perforator bodies toprevent the ingress of well fluid which would damage lor otherwise bedetrimental to the perforating action of the charges. The presentinvention is particularly concerned with new and improved iiuid sealingmeans for such purposes.

Heretofore the discharge openings of well perforating gun units orbodies have been-sealed byl various types 4of sealing elements 'whichwere adapted to be vdislodged by the explosive force or bythe impact ofthe perforator bullet, and to fall from. the gun vmuzzle or Adischargeopening'into the well casing. Frequently such dislodged seals i hampersubsequentv operations in such ways as by becoming jammed between thegun body and surrounding well Wall or casing, or by becoming entrainedin the upward flow of well fluid and blocking or clogging the flowtherefrom or by interfering with the action of valves or the likemechanisms. The presence ofsuch sealing elements in the well bore orcasing is therefore objectionable.

In an effort to overcome or eliminate some of the before-mentionedobjectionable features attendant upon the presence of dislodged fluidsealing bodies in the well or casing, frangible sealing members, usuallyin the form of discs of cup shaped members made of brass, copper, steeland the like, have been applied to the discharge open- Such seals arefractured, torn-and broken by the bullet or explosive force, and leaveas a residue seal fragments which are materially less of a threat tosubsequent well-operations. Never-f" tireless, such fragmntsarefrequenuy'objecncnable in size, and 'in some `instances Ythe seal-mayonlybe pierced, leaving atorn body? in place in v`the gun body,theserrated edgesof which maybe of greater operational hazard than lthe.presence of an Vundamagedbutv dislodged seal.

Sealing devices, heretofore employed, were usually either substantiallyflat or slightly dished metal discs having integrally formedskirtedperipheries constituting annular sealingy Wallsengag'eable withthe inside surfaceof the walls of the discharge openings. AThis form ofsealing device requires considerable tensilestrength inthe sea-l lmaterial to withstand the bending stresses set up Within the device bythefiuidpressures encountered within the well borehole, and `thethickness and type of material chosen for use with such forms of sealingdevices'nn1st-necessarilyha-ve considerable .ductility and tensilestrength. Sealing` devices of this kind are not destroyed b-y the firingof the perforator gun or shaped charge but usually are onlyperforatedtorn, or merely dislodgedas a result of which they offer thedisadvantages and hazards hereinbefore mentioned.

It is, therefore, an object ofthis invention to provide` asealing deviceof they.: character described in which many of the undesirable andlimiting features heretofore prevalent .in such uid seals have beeneliminated. y

It is also an object to provide a friable or disintegrable fluid sealingdevice which, upon impact of a bul-letor an explosive force thereon,will be substantially completely destroyed and thus Will leavesubstantially'no debris or pieces of appreciable size in the well, ascontrasted with the .frangible or ductile seals heretofore employed,

which are only fractured, torn, orbroken into .fragments of substantialsize, or of seals which are dislodged intact from the discharge opening.

Another object of the invention is to provide a fluid seal member ofuniform conguration free from depending edges or skirts which may beretained in the kdischarge opening or b e discharged therefrom as aWhole ring or. as fragments of' a ring. The present seal body is ofsuch'character that the entire seal is subjected to substantially luniform disintegrating' force sor that disintegration is complete anddistinctfromy rupture or fragmentation commonfin the use of soz-calledfrangible seals.

Affurther object-of the invention -is to prove y a seal, theconfiguration andcurvature of which is such as yto, provide adistribution of. the. compressive forces whereby the resultant forceswill .act against the'walls of the discharge opening to which it is ttedin such manner to withstand great pressures without requiringproportionate strength of material, and whereby such forces will act toaid in the sea-ling of the discharge aperture, the sealing pressurebeing effectively increased as the pressure to be sealed againstincreases.

The objects of the invention are accomplished, in general, by composingthe fluid seal device of a friable, brittle material such as cast iron,glass, micalex or ceramics and the like, as distinct from ductilematerial such as copper, brass, steel or rubber, by reason of which suchmaterial tears and shears rather than disintegrates.7 The objects arealso accomplished by the use of a dome or hemispherical shape for theseal body, the edges of which thrust perpendicularly against an annularseating surface formed in the body of the gun in such manner as totransfer the cornpressive forces from the sealing member assubstantially pure compression forces to the said seating surface byvirtue of which the tensile strength of the material of which thesealing device is composed may be substantially less than otherwisewould be required.

These and other objects, advantages and features of novelty will beevident hereinafter.

The drawings, which show by way of illustration, a preferred embodimentof the invention and in which like reference characters, designate thesame or similar parts throughout the several views.

Figure 1 is a fragmentary longitudinal sectional view of one form ofperiorating gun equipped with the seal of the present invention.

Figure 2 is an enlarged detail transverse section taken on line 2-2 ofFigure 1.

The perforating apparatus, here shown by way of example as one of themany types of such apparatus to which the seals of the present inventionmay be employed, is one utilizing shaped charges as distinct from agun-type perforator using cartridges and bullets. However, it is to beunderstood that the present seal is advantageously applicable to eithertype of perforator.

The perforator apparatus, here shown by way of example and to which theseals of the present invention are applied, comprises a hollow,substantially cylindrical body or shell I@ closed at its lower end by asuitable formed tapered bull plug II. The relatively thick wall of thecylindrical body I has a series of longitudinallyspacedradially-directed ports or discharge openings I2 extending therethroughto the inside of the central bore or chamber I3, each opening beingenlarged on the outside by a relatively short counterbore I4 of slightlyincreased inside diameter. An outwardly facing inclined shoulder I5,having a surface of frusto-conical form, interconnects the inner portionof the discharge opening I2 with its outer counterbore IA. A series of aplurality of discharge openings such as that shown at I2, I (only two ofwhich are shown in Figure l for convenience of illustration, duplicateones thereof having been omitted) may be arranged in any desiredpattern. One suitable pattern which is frequently used is that rformedby spacing the discharge openings in a spiral arrangement along thelength of the body.

A perforating unit such as shown at It is located opposite and inalignment with each discharge opening. Such units are here disclosed inoutline only, and may be either shaped charge units or gun type unitsincluding cartridges and perforating bullets as desired. In either case,

the perforating unit is so mounted that the bullet or the jet-shapedblast from the shaped charge unit will be directed outward in a radialdirection through the center of the discharge opening i2. In the form ofgun here shown, the inner wall of the body IB opposite each of thedischarge openings l2 is provided with a radially directed recess I7,the adjacent rear end I8 of each of the shaped charge units IS beingcooperatively shaped to fit within and be retained by the recess. Asindicated at 2li, the charge unit may include a front retainer sleevehaving the approximate shape of a truncated cone and which extendsforwardly from the front edge of the body of the unit I5 to engage theinner end of the discharge opening I2, serving thereby to support and tocenter the adjacent forward end of the charge i3 in accurate axialalignment relative to the center of the discharge opening I2.

For further details of the particular gun herein illustrated, referencemay be had to the copending application of Will H. Lindsay and Robert A.Phillips, Serial No. 106,567, led July 25, 1949,

In the form of perforating devices here illustrated, the upper end ofthe body i0 is closed by a disc 2i, through the center of which extendsa fuse 22 leading to the shaped charge perforating units I6. An electricdetonator cap 23 is mounted upon the disc 2i and is connected to andcontrolled by an insulated electrical conductor 24. For closing theupper end of the body lll and securing the disc 2| in place, a threadedsleeve 2d is provided, into which is secured a subconnection or casing25 which may contain the detonating control mechanism (not shown), and aconductor cable 26 is anchored in a cable socket 25 integral with thetop of the casing 25. by means of which the gun may be lowered into andremoved from the well. It will be understood that the present inventionis not concerned with such structure of the firing control mechanism,electrical connections and other details thereof, and that anyequivalent or suitable structure and arrangement of such parts may beemployed as desired.

Prior to the time of detonation of the charge or cartridge I, it isessential that the discharge openings I2 be provided with a fluid-tightclosure against the admission of well fluid or other substance whichmight damage the cartridge or propellant charge or in any way interferewith the full, complete and eiiicient firing or detonation thereof. Forexample, in the case of the shaped charge as illustrated, the shapedcavity and the space ahead of it must be kept free of liquid which wouldinterfere with the proper jet action thereof. Accordingly, a fluidtight, pressure-resistant seal for the opening I2 is provided in theform of a friable, dome-shaped cap 30. The shape or structure of the cap30 is preferably that of a segment of a spherical shell, having innerand outer spherical surfaces of uniform radius ci curvature andpositioned with its convex surface racing outwardly. Since, as beforenoted, it is desirable not only to remove or pierce the seal upondetonation of the charge or cartridge, but to completely destroy ordisintegrate the material thereof, the cap is preferably formed of afriable material which will readily disintegrate into ne particles uponimpact of a bullet or explosive blast, as distinct from merely frangiblematerial of considerable relative tensile strength and ductility such asbrass, copper, steel or the like. Materials found to have the shatteringand disintegrating qualities here desired are those such as glass, castYiron, 'micalex and porcelain and other ceramics of various kinds. Suchrmaterials have been.,found successful forthe purpose and are herereferred to as'suitable for use in the manufacture of the present seal.

Preferably, the dome-like body of the present sealing member 30 isprovided with an edge 3l having a ,surface which constitutes a frustumof a cone, the apex of which coincides approximately withvthefcenter ofcurvature of the spherical inner `and outer surfaces of the body itself.With the hereinbefore mentioned materials, a l 1A, thickness of domematerial has been found `suitable for a seal of this shape having adiameter of approximately 1%f diameter.y While expedients offmanufacturemay vdictate various departures fromthe uniform internal and externalcurvatures` and thus a variation from La uniform thickness of the bodyof the seal as here specied and may vsimilarly dictate variations in theexact angularity of the frusto-conical edge surface, it will beunderstood that such formation is now deemed advantageous and desirable.However, it will be understood that the invention is in no way limitedto the exact configuration referred to except as hereinafter indicatedin the claims. Thus, the invention may be practiced, utilizing variouscurvatures, thicknesses and edge dispositions for the sealing member 30as determined by one skilled in the art.

By further reference to Figure 2 of the drawings, it will be noted thatthe surface of the shoulder I5 at the juncture of the opening I2 and itsouter counterbore I4 also takes the form of a frustum of a cone, theapex and axis of which coincide with the axis of the opening I2 and thecounterbore I4'. As here shown, and as preferred in the practice of theinvention, the apex angle included between opposite sides of thefrusto-conical surface of the shoulder I4 approximates the angleincluded between opposite sides of the frusto-conical edge surface ofthe body of the seal. An included angle of 140 degrees, taken fromapproximately the center of curvature of the dome, is preferred. Ifdesired, these apex angles may vary, as for instance, such variation asis necessary to make allowance for the thickness of sealing materialtherebetween after the seal is located and secured, thus providing asaccurate conformity as possible between the surface of the seal edge 3Iand the shoulder surface I5. However, for most cases, and bearing inmind the size of the parts and the diiiculties of manufacture, asubstantial equality of included apex angle will suffice. The inventionis, of course, not limited to such specified angularty, but these may bevaried somewhat without sacrifice of thinness of the seal member.

In assembling the seal member 30 within the counterbore I4 of thedischarge opening I2, a gasket ring 32 of rubber or like flexible orresilient packing material is employed. The ring is preferably formedwith a U-shaped, annular channel 33 to receive the edges 3I of the sealmember 30 and to surround and cover a marginal portion of such edges inself-sealing engagement. The gasket ring is provided with an outerfillet shaped or meniscus like leg portion 34 of increasing thicknesstoward its outer periphery 35 to conform with the outward divergence ofthe surface of the seal with respect to the inside cylindrical surfaceof the walls of the counterbore I4. The outwardly facing surface of thethickened extremity of the packing ring is preferably curved inwardlyto. provide an annular. fillet-like body making a feather edgeengagement with both the outside surface of the seal member and withkthe inner cylindrical surface-of the counterbore wall. Such arrangementprovides for -the pressingof such edgesagainst such surfaces upon theapplication of uid pressure thereto, thereby providing a self-sealingaction to the packing ring.

In the form of the invention herein illustrated, the angle of-inclination of the `frusto-conical edges of the seal member 30 and ofthe shoulder I5 is substantially equal and is shown as substantially 20degrees with respect to the-diametrical plane of the opening I2. While`the angularity-of the shoulder I5 and that of the edge surface 3| ofthe seal member 30 are not necessarily identical, the arrangement, asdisclosed, has been found well suited to the functions requiredand theconditions encountered -in- -a uid filled borehole. In considering theeffect ofthe shape and angularity of the seal member as hereinbeforedescribed, it will be'noted that uponl being subjected to outside fluidpressures, the dome-like configuration will result in the setting up ofcircumferential compressional forces through 'the body of the sealmember, which forces are directed to the edges thereof, where theangularity of the edge 3I in conjunction with the angularity of theshoulder I5 will result in the transfer of such forces, in the form ofsubstantially pure compression, to the surface of the shoulder I5 of thedischarge opening. Thus, the material of the seal member, not beingsubjected to bending stresses, may have a minimum of tensile strengthwhile still withstanding the required compression stress withoutbreakage. While the angles herein suggested are believed preferable inmost instances, circumstances and choice of material may dictate slightvariations therefrom. In any event, it is to be noted that a seal memberformed as a segment of a spherical shell, as hereinbefore described,will be subjected to compressional stresses only, thereby permitting itsformation of a brittle and disintegrable material as herein set forth.

While the invention has been herein described in what is now consideredto be its preferred form, it is to be understood that the invention isnot limited to the specific or exact details of such form, but coversall changes, modifications and adaptations within the scope of theappended claims.

What is claimed is:

1. The combination with the discharge opening of an explosive wellperforator body having a coaxial counterbore for said opening adjacentthe outer end thereof and an outwardly facing, outwardly divergingfrusto-conical shoulder surface at the juncture of the said dischargeopening and the said outer counterbore, of a sealing member havingsubstantially the shape of a segment of a spherical shell composed ofmaterial disintegrable upon impact, said member being bounded by acircular, frusto-conical edge surface, having an apex substantiallycoinciding with the center of curvature of said shell, and saidfrusto-conical shoulder surface being formed to substantially conform tothe said edge surface; and an encircling, U-shaped seating and packingring of flexible material interengaging said shoulder and said edgesurfaces, the outer leg of the U of said ring being of greater thicknesstoward its periphery and extending outwardly to lie over a marginalportion of the outer face of the member and make sealing contact with aportion of the inside cylindrical surface of said counterbore.

2. The combination with the discharge opening of an explosive Wellperforator body having a coaxial counterbore for said opening adjacentthe outer end thereof and an outwardly facing, outwardly dvergingfrusto-conical shoulder surface at the juncture of the said dischargeopening and the said outer counterbore, the angularity of the surface ofwhich is approximately 20 degrees to a plane perpendicular to the axisof said discharge opening, of a sealing member having substantially theshape of a segment of a spherical shell composed of materialdisintegrable upon impact, said member being bounded by a circular,frusta-conical edge surface, substantially conforming to the saidsurface of said :truste-conical shoulder; and an encircling, U-shapedseating and packing ring of flexible material interengaging saidshoulder and said edge surfaces, the outer leg of the U of said ringbeing of greater thickness toward its periphery and extending outwardlyto lie over a marginal portion of the outer face of the member and makesealing Contact with a portion of the inside cylindrical surface of saidcounterbore.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 663,879 Gallup Dec. 18, 1900 1,684,292 Turnquist Sept. 11,1928 1,669,685 Weber May 15, 1928 2,142,572 Metzner Jan. 3, 19392,146,586 Evans Feb. 7, 1939 2,216,144 Turechek Oct. 1, 1940 2,250,056Alexander July 22, 1941 2,258,724 Wagner et al. Oct. 14, 1941 2,261,035Miller Oct. 28, 1941 2,280,183 Bennett Apr. 21, 1942 2,311,077 OldhamFeb. 16, 1943 2,328,247 Alexander Aug. 31, 1943 2,408,774 Goddard et a1.Oct. 8, 1946 2,426,521 Parker Aug. 26, 1947

